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These procedures were designed and tested for internal use by OSHA personnel. Mention of any company name or commercial product does not constitute endorsement by OSHA.

Samples are collected by drawing known volumes of air through glass fiber filters. The filters are extracted with acetonitrile and analyzed by high performance liquid chromatography (HPLC) using an ultraviolet detector (UV).

Recommended air volume and sampling rate:

60 L at 1.0 L/min

Detection limit of the overall procedure (based on the recommended air volume and the analytical detection limit):

0.14 mg/m3

Status of method:

Stopgap method. This method has been partially evaluated and is presented for information and trial use only.

This evaluation was undertaken because OSHA recently adopted the temephos TLV as a PEL. Glass fiber filters were tested as an effective sampling device for temephos.

1.1.2. Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy.)

The oral LD50 in male and female rats is 8600 and 13000 mg/kg respectively. (Ref. 5.1.) All animal species tested tolerated 10 mg/kg without clinical effect, and 1 mg/kg without effect on cholinesterase activity (Ref. 5.2.). Humans have tolerated an oral dose of 256 mg/man/day for 5 days or 64 mg/man/day for four weeks without detected effects on plasma cholinesterase or red blood cells. (Ref. 5.2.)

1.1.3. Potential workplace exposure

Temephos is a cholinesterase inhibiting insecticide. No information was available on the number of workers that may be exposed to temephos. There was an estimated 1.5×108 grams produced in 1972 by the U.S.

1.1.4. Physical properties (Ref. 5.1. to 5.4.)

CAS number:

3383-96-8

IMIS number:

T195

Molecular weight:

466.46

Molecular formula:

C16H20O6P2S3

Melting point:

30.0-30.5°C

Solubility:

Soluble in acetonitrile, carbon tetrachloride, ether, dichloroethane, toluene; almost insoluble in water and hexane; insoluble in methylcyclohexane

2.3.1. Immediately before sampling, remove the plastic plugs from the cassette.

2.3.2. Attach the cassette to the sampling pump with flexible tubing.

2.3.3. Attach the cassette vertically in the employee's breathing zone in such a manner that it does not impede work performance.

2.3.4. After sampling for the appropriate time, remove the cassette and seal with plastic plugs.

2.3.5. Wrap each sample end-to-end with an OSHA seal (Form 21).

2.3.6. Record the air volume for each sample, and list any possible interferences.

2.3.7. Submit at least one blank for each set of samples. Handle the blank in the same manner as the samples, except no air is drawn through it.

2.3.8. Submit bulk samples for analysis in a separate container. Do not ship with air samples.

2.4. Extraction efficiency

Twenty-four glass fiber filters were each liquid spiked with 12 µL of a 25.47 mg/mL solution of temephos. These samples were allowed to equilibrate overnight in a drawer at ambient temperature. The next day six samples were each desorbed with 4.0 mL of acetonitrile, shaken for 30 min and analyzed as in Section 3. The results are listed in Table 2.4.

Table 2.4.
Extraction Efficiency

Amount

Amount

%

Sample #

Spiked, µg

Found, µg

Recovered

Ex1
Ex2
Ex3
Ex4
Ex5
Ex6

305.6
305.6
305.6
305.6
305.6
305.6

292.7
288.9
286.9
294.8
303.4
312.4

95.8
94.5
93.9
96.5
99.3
102.2

Average = 97.0

2.5. Retention efficiency

The remaining eighteen spiked glass fiber filters from section 2.4. were placed on a humid air generator and 60 L of humid air (~78% relative humidity) were drawn through each filter at 1 L/min. Six of the filters were each desorbed with 4.0 mL of acetonitrile, shaken for 30 min and then analyzed as in Section 3. The results are listed in Table 2.5. The remaining samples were stored, six in a drawer at ambient temperature and six in a freezer, for use in the storage study below.

Table 2.5.
Retention Efficiency

Amount

Amount

%

Sample #

Spiked, µg

Found, µg

Recovered

R1
R2
R3
R4
R5
R6

305.6
305.6
305.6
305.6
305.6
305.6

294.2
290.5
294.3
310.0
309.2
294.8

96.3
95.1
96.3
101.4
101.2
96.5

Average = 97.8

2.6. Sample storage

After four days of storage, six samples were each desorbed with 4.0 mL of acetonitrile, shaken for 30 min and then analyzed as in Section 3. Three of the samples were from ambient storage and the other three were from the freezer storage samples. The remaining samples were analyzed after seven days of storage. The results are given in Tables 2.6.1. and 2.6.2.

Table 2.6.1.
Ambient Storage

Days

Amount

Amount

%

Stored

Spiked, µg

Found, µg

Recovered

4
4
4
7
7
7

305.6
305.6
305.6
305.6
305.6
305.6

342.4
296.0
305.6
298.7
311.2
293.9

112.0
96.9
100.0
97.7
101.8
96.2

Average of four days = 103.0

Average of seven days = 98.6

Table 2.6.2.
Freezer Storage

Days

Amount

Amount

%

Stored

Spiked, µg

Found, µg

Recovered

4
4
4
7
7
7

305.6
305.6
305.6
305.6
305.6
305.6

304.0
297.5
290.6
306.8
284.1
302.4

99.5
97.3
95.1
100.4
93.0
99.0

Average of four days = 97.3

Average of seven days = 97.5

2.7. Recommended air volume and sampling rate

2.7.1. The recommended air volume is 60 L.

2.7.2. The recommended flow rate is 1.0 L/min.

2.8. Interferences (sampling)

It is not known if any compounds will interfere with the collection of temephos. Any suspected interferences should be reported to the laboratory.

2.9. Safety precautions (sampling)

2.9.1. Attach the sampling equipment in such a manner that it will not interfere with work performance or employee safety.

2.9.2. Follow all safety practices that apply to the work area being sampled.

3. Analytical Procedure

3.1. Apparatus

3.1.1. A balance capable of weighing to the nearest tenth of a milligram. A Mettler HL52 balance was used in this evaluation.

3.1.2. A mechanical shaker.

3.1.3. An HPLC equipped with a UV detector. A Hewlett Packard (HP) 1090M equipped with an autosampler and diode array detector was used in this evaluation.

3.1.4. An HPLC column capable of separating temephos from any interferences. A 100 mm × 2.1 mm i.d. Hypersil ODS liquid chromatography column was used in this evaluation.

3.1.5. An electronic integrator, or some other suitable means for measuring detector response. The Hewlett-Packard 1090M Data System was used in this evaluation.

3.1.6. Volumetric flasks and pipets.

3.1.7. Vials, 2-mL and 20-mL.

3.2. Reagents

3.2.1. Acetonitrile, HPLC grade. This was obtained from Burdick and Jackson for this evaluation.

3.2.2. Temephos, reagent grade. A standard obtained from EPA (EPA # 0020, 98.34% purity) was used in this evaluation.

3.2.3. Water, HPLC grade, Milli-Q filtered water, Millipore Inc.

3.3. Standard preparation

Prepare temephos stock standards by weighing 10 to 15 mg of temephos. Transfer the temephos to separate 10-mL volumetric flasks, and add acetonitrile to the mark. Make working range standards of 2.0 to 185 µg/mL by diluting the stock standards with acetonitrile. Store stock and diluted standards in a freezer.

3.4. Sample preparation

3.4.1. Transfer the glass fiber filter to a 20-mL vial.

3.4.2. Add 4.0 mL of acetonitrile to each vial and seal with a Teflon-lined cap.

3.4.3. Shake the vials for 30 minutes on a mechanical shaker.

3.4.4. If necessary, transfer the samples to 2-ml vials for use on an HP autosampler.

3.5. Analysis

3.5.1. Instrument conditions

Column:

100 mm × 2.1 mm hypersil ods

Mobile phase:

60% acetonitrile 40% water

Flow rate:

0.3 ml/min

Wavelength:

200 nm

Retention time:

6.1 min

Injection volume:

1.0 µl

3.5.2. Chromatogram (Figure 3.)

3.6. Interferences (analytical)

3.6.1. Any collected compound having a similar retention time to that of the analyte is a potential interference.

3.6.2. HPLC conditions may generally be varied to circumvent interferences.

3.6.3. Retention time on a single column is not proof of chemical identity. Analysis on an alternate HPLC column and confirmation by mass spectrometry are additional means of identification.